How can we improve the Microsoft Edge developer experience?

APNG (animated PNG) images support [Firefox and Safari 8 support it]

APNG is an extension of the Portable Network Graphics (PNG) format, adding support for animated images. It is intended to be a replacement for simple animated images that have traditionally used the GIF format, while adding support for 24-bit images and 8-bit transparency. APNG is backwards-compatible with PNG; any PNG decoder should be able to ignore the APNG-specific chunks and display a single image.

Fwiw, even if it may look unreasonable to use APNG on _web pages_ in terms of traffic, it still makes perfect sense for _browser addons_ where quality animated graphics may be _built-in_, so there is no perceived-performance-related overhead of _downloading_ graphics, it’s downloaded just _once_ — when the extension is installed or updated.

Microsoft can't simply implement APNG.
First, they want to promote their JPEG XR (like Google do same with WebP).
Second, they getting money as member of MPEG-LA, and situation when you can choose only between old, big and laggy GIF and modern MPEG-formats is a win-win.
Third, GIF animation in IE (and Edge) done as a dirty hack — GIF in Windows by default has no animation, and they do not want APNG because then it must be done as system-wide solution or as slow and hard-to-maintain hack too. That's requires work on core, which noone wants (and in current MS actually noone cans) to do.
And fourth is a watching against Google. If Big Brother will introduce animated PNGs in their browser and it will be popular on services like imgur and FB, then MS will do it too. But Google want to promote their WebP/WebM 'cause Google not getting as much money from MPEG-LA as MS gets.

So there's almost question about money, not about good things on web.
Wanna change it — switch to Firefox/Palemoon, boycott Edge and Chrome-based browsers if do not want support business giants ambitions. If not — all other web engines will die like Opera Presto and then monopoly (or "duopoly") will make a web is a very uncomfortable place.